[Dovecot] AUTH PLAIN error with Thunderbird and Dovecot 1.2

[Bernhard Schmidt]

Hi,

a few days ago I started to get some complaints about authentication
delays from Thunderbird POP3 users. After some debugging it turned out
that the problem was introduced somewhere between 1.2rc3 and 1.2rc7
(1.2.0 is still affected).

A session with Thunderbird 2.0.0.22 against 1.2rc3 looks like this:

<<< +OK Dovecot ready.
>>> CAPA
<<< +OK
<<< CAPA
<<< TOP
<<< UIDL
<<< RESP-CODES
<<< PIPELINING
<<< STLS
<<< USER
<<< SASL PLAIN LOGIN
<<< .
>>> AUTH PLAIN
<<< + 
>>> <base64>
<<< +OK Logged in.

and with 1.2.0 (same client, same config, just replaced the server
binaries)

<<< +OK Dovecot ready.
>>> CAPA
<<< +OK
<<< CAPA
<<< TOP
<<< UIDL
<<< RESP-CODES
<<< PIPELINING
<<< STLS
<<< USER
<<< SASL PLAIN LOGIN
<<< .
>>> AUTH PLAIN
[ 2 seconds delay ]
<<< -ERR Authentication failed.
>>> AUTH LOGIN
[ 5 seconds delay ]
<<< + <base64>
>>> <base64>
<<< + <base64>
>>> <base64>
<<< +OK Logged in.

In the log I see

mail dovecot: auth(default): plain(?,77.2.39.xx): invalid input

Does anyone have an idea? 

# dovecot -n
# 1.2.0: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.28.2 x86_64 Debian squeeze/sid ext4
protocols: imap imaps pop3 pop3s managesieve
listen: *, [::]
ssl_cert_file: /etc/ssl/private/pop3.mucip.net.crt
ssl_key_file: /etc/ssl/private/pop3.mucip.net.key
disable_plaintext_auth: no
login_dir: /var/run/dovecot/login
login_executable(default): /usr/lib/dovecot/dovecot/imap-login
login_executable(imap): /usr/lib/dovecot/dovecot/imap-login
login_executable(pop3): /usr/lib/dovecot/dovecot/pop3-login
login_executable(managesieve):
/usr/lib/dovecot/dovecot/managesieve-login
login_process_per_connection: no
verbose_proctitle: yes
mail_uid: 5000
mail_gid: 5000
mail_location:
maildir:/var/mail/vmail/%1u/%u:INDEX=/var/cache/dovecot/%1u/%u
maildir_stat_dirs: yes
mail_executable(default): /usr/lib/dovecot/dovecot/imap
mail_executable(imap): /usr/lib/dovecot/dovecot/imap
mail_executable(pop3): /usr/lib/dovecot/dovecot/pop3
mail_executable(managesieve): /usr/lib/dovecot/dovecot/managesieve
mail_plugins(default): quota imap_quota fts fts_squat
mail_plugins(imap): quota imap_quota fts fts_squat
mail_plugins(pop3): 
mail_plugins(managesieve): 
mail_plugin_dir(default): /usr/lib/dovecot/imap
mail_plugin_dir(imap): /usr/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/pop3
mail_plugin_dir(managesieve): /usr/lib/dovecot/managesieve
imap_idle_notify_interval(default): 900
imap_idle_notify_interval(imap): 900
imap_idle_notify_interval(pop3): 120
imap_idle_notify_interval(managesieve): 120
auth default:
  mechanisms: plain login
  verbose: yes
  passdb:
    driver: ldap
    args: /etc/dovecot/dovecot-ldap.conf
  userdb:
    driver: ldap
    args: /etc/dovecot/dovecot-ldap.conf
  socket:
    type: listen
    client:
      path: /var/spool/postfix-mailout/private/auth
      mode: 432
      user: postfix
      group: postfix
    master:
      path: /var/run/dovecot/auth-master
      mode: 384
      user: vmail
plugin:
  quota: maildir
  quota_rule: *:storage=500M


Thanks,
Bernhard